First I hate this thing wish I never bought it.
2015 artic cat 500
900 miles need the entire clutch system replaced internal and external parts

Now when I try to start it just clicks unless I jump the solonid (already replaced with new same issue)

When it does start it only sometimes idles. sometimes gotta hold the thottle open other times idiles fine.

What do I look for?
Starting issue and idling issue (intermittent idle problems)

 

Have you checked the plug? they seem to foul if they are not allowed to warm up to operating temp before you shut off. like when your loading and unloading.
As for teh clutch what went the belt and took out the clutch? were u using lo range when you were suppose to? thats the usual reason a belt will fail.
have you had your battery load tested? with the year of the machine i would almost bet its due for a new one. I have replaced my 2014 2x now and now keep it on a maintainer as the cat charging system is barley enough to keep it charged with lights on let alone using a winch or other accessory. By jumping the solenoid you just bypass the extra electrical making it easier to start.

My 500 is the same as yours and gets used like they were designed to and never had a issue. I don't baby it but keep the maintenance up on it.

Pictures of the clutch would also help

 

subscribed, this seems like a very interesting thread